Temperature control of light modulating fluid in a light valve projection system

Abstract

A light valve projector system having an improved apparatus for heating the light modulating fluid. The light modulating fluid is heated with near infra-red radiation which passes though the enclosing glass envelope and which is absorbed by the light modulating fluid.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is as follows: 
     
       1. A light valve projector system in which information is impressed on a light modulating fluid overlying a disk wherein incident visible light is modulated by the information and projected onto a viewing screen, said disk rotating within a glass envelope which forms a reservoir for said light modulating fluid through which said disk rotates in order to deposit a control layer of said fluid on said disk, the control layer being rotated to a raster area within which the information is written by the deposition of electric charge along scanning lines so as to form orthogonally related diffraction gratings, and infra-red heating means external to said envelope and positioned adjacent said reservoir for heating said fluid, wherein said heating means provides radiation at wavelengths which are transmitted through said envelope without producing thermal stress in said envelope and at wavelengths which heat said light modulating fluid to control the viscosity and light transfer characteristic thereof. 
     
     
       2. The light valve projector system recited in claim 1 further including a means for focussing infra-red radiation from said infra-red heating means upon said light modulating fluid. 
     
     
       3. The light valve projector system recited in claim 2 wherein said means for focussing is a reflector located adjacent to the infra-red radiation heating means. 
     
     
       4. The light valve projector system recited in claim 2 wherein said means for focusing is a lens located adjacent to said infra-red radiation heating means. 
     
     
       5. The light valve projector system recited in claim 1 wherein said infra-red heating means comprises a plurality of sources located so as to provide more uniform heating of said light modulating fluid. 
     
     
       6. The light valve projector system recited in claim 1 wherein said infra-red heating means comprises at least one incandescent lamp. 
     
     
       7. The light valve projector system recited in claim 1 wherein said infra-red heating means comprises a source of light having a broad spectrum and a means for filtering out visible light from said source. 
     
     
       8. The light valve projector system recited in claim 1 further comprising means for measuring the temperature of the fluid in said reservoir. 
     
     
       9. The light valve projector system recited in claim 1 wherein the wavelengths of said infra-red heating means encompass the wavelengths transmitted through the envelope above about 1.0 microns. 
     
     
       10. The light valve projector system recited in claim 9 wherein said light modulating fluid has a temperature of about 60° C.